This invention relates generally to mirror systems for vehicles and more particularly to such mirror systems having controls for adjustment of the reflectance level of one or more mirrors. The invention is especially adapted to mirror systems utilizing continuously variable reflectance elements such as electrochromic elements.
Automatic rearview mirrors which sense glare-producing light and ambient light conditions and which automatically control the reflectivity level of the mirror have become sophisticated in establishing an optimum reflectivity level. Examples of such systems are included in U.S. Pat. No. 4,793 690 to Edward A. Gahan et al for a REARVIEW MIRROR CONTROL CIRCUIT, and U.S. Pat. No. 4,886,960 to Keith W. Molyneux et al. for a CONTROL CIRCUIT FOR AN AUTOMATIC REARVIEW MIRROR. Such systems typically provide a manual sensitivity adjustment. The control then automatically establishes the reflectivity of the reflectance element based upon the sensed level of ambient light and glare-producing light, as well as the sensitivity level selected by the driver.
While such automatic controls are very satisfactory for many automotive applications, especially for automobiles and small trucks, they are not necessarily desirable for all applications. Truck drivers and other professional drivers use their mirrors as a primary driving aid and, as such, use their mirrors to a much greater extent than do ordinary drivers. Because of the primary importance served by the rearview mirrors to professional drivers, such drivers desire greater personal control over operation of the mirror. Mirror glare is an especially severe problem for professional drivers who drive for long periods and are more likely to be driving during nighttime hours. Such glare creates eye fatigue which adds to the overall fatigue experienced during long trips. Therefore, what may be a mere annoyance to a casual driver, may be a safety problem for the professional driver.
Non-professional drivers also often desire greater user control over the reflectance level of the mirrors. Remotely actuated mirrors have been provided which allow the driver to actuate a two-state, prism-type mirror between states. While such remotely actuated mirrors put control of the mirror in the hands of the driver, they do little more than duplicate the manual flipping of a conventional mechanical rearview mirror.